314 Proceedings of Indiana Academy of Science 



greater among the plants of the littoral than in the pelagic region of 

 the lake. 



Birge and Juday^ report a diurnal oxygen pulse in Lake Mendota. 

 They determined the amount of oxygen in the upper three meters of 

 water just after 6 a. m. and a little before 5 p. m. They found a slight 

 variation (.2 cc. per 1.) at the surface, but a very decided pulse (1.8 cc. 

 per 1.) at the 1.5 m. level. Their observations were made September 

 20, 21, and 22. 



* Birge, E. A., and Juday, C. 1911. The Inland Lakes of Wisconsin. The dis- 

 solved gases of the water. Bui. No. XXII, Wis. Geol. and Nat. Hist. Survey, p. 43. 



